Serviceable Battery Pack With Cell-Level Replacement and Thermal Control
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Solution Overview
Problem
Current battery packs in electrified vehicles are not serviceable, leading to reduced lifespan due to unbalanced cells and inefficient thermal management, especially in varying climates, which affects efficiency and longevity.
Innovation Solution
A battery pack design with individually removable cells, a thermal conditioning unit for temperature regulation, and a tensioning mechanism for secure cell placement without permanent deformation, along with a sealed air flow system for efficient heat exchange and insulation to prevent thermal bridging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery cells are secured in an enclosed housing for protection, then reliability and protection from elements is improved, but thermal management capability deteriorates due to restricted heat exchange
Solution Approach 1:
The patent uses a housing with selective permeability - walls that are substantially impermeable to liquid moisture but permeable to water vapor. This allows the housing to protect cells from liquid damage while permitting evaporative cooling and heat exchange, resolving the contradiction between protection and thermal management
Solution Approach 2:
The housing incorporates porous or vapor-permeable materials that allow water vapor transmission while blocking liquid water. This enables moisture protection while maintaining thermal exchange capabilities through controlled porosity
2Temperature
If insulation is added to maintain consistent temperature regardless of outside conditions, then thermal stability is improved, but passive cooling capability deteriorates when outside conditions are favorable
Solution Approach 1:
The housing's thermal parameters are made variable through its selective permeability characteristics. The vapor-permeable walls dynamically adjust thermal exchange based on environmental conditions, allowing passive cooling when favorable while providing insulation when needed, thus resolving the contradiction between thermal stability and passive cooling efficiency
3Stability of the object's composition
If mounting brackets are used to secure battery pack to vehicle, then mechanical stability is improved, but thermal bridging increases leading to heat loss
Solution Approach 1:
The patent introduces thermal break elements as intermediaries between the metal mounting brackets and the battery pack housing. These elements (such as plastic or rubber inserts, foam material, or air gaps) mediate the thermal transfer, preventing direct thermal bridging while maintaining mechanical attachment stability
4Power
If cells are arranged in series to achieve high voltage, then power output is improved, but system reliability deteriorates due to the weakest link effect
Solution Approach 1:
The patent segments the battery pack into independently replaceable cell modules. When a cell degrades, only that specific module needs replacement rather than the entire pack. This segmentation maintains high voltage through series arrangement while improving reliability by enabling selective replacement of failed cells
5Stability of the object's composition
If a tensioning mechanism is used to secure cells, then mechanical stability is improved, but device complexity increases
Solution Approach 1:
The tensioning mechanism is designed to be self-adjusting through elastic deformation of the housing or tension bars. The system automatically maintains proper cell tension without requiring complex external actuators or manual adjustment mechanisms, thus achieving mechanical stability while minimizing added complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for serviceable battery packs with improved cell replacement and thermal management, enhancing the lifespan and efficiency of battery packs across different climates by maintaining optimal temperature and reducing the impact of cell imbalance.
Implementation Method 1
a thermal fluid conditioning unit configured to (i) circulate the heat transfer medium in the housing and adapted to convey heat and (ii) regulate a temperature of the battery cells
Implementation Method 2
a fan in the container and located outwardly of the battery-receiving volume... wherein the fan is configured to generate a flow of the heat transfer medium within the container
Implementation Method 3
a heat exchanger in the container and arranged in series with the fan, wherein the heat exchanger is configured to add or extract heat from the gaseous heat transfer medium
Implementation Method 4
The array of the rails is supported in spaced relation to the container by blocks of an insulating material having a low thermal conductivity
Implementation Method 5
a desiccant packet is contained somewhere within the inside air volume to prevent condensation from occurring
Data Source
AI summary
A fully serviceable battery pack architecture can be serviced down to the cell level in a convenient and timely manner without needing to remove the complete battery pack from the vehicle or perform an extensive amount of labor. Such architecture is considered a special cell to pack technology that the cells are held in place by a compressive force providing static friction. The design of the tensioning mechanism allows for such tension to be released and reapplied by a technician using basic tools. A fan circulates the air inside the battery pack in a closed loop through a heat exchanger containing another fluid providing heating and cooling to the pack. Extensive insulation work and minimizing thermal bridging with the environment allows for superior performance, minimizing seasonal range inconsistency, improved efficiency and longevity of such pack in harsh climates where exposure to extreme cold or heat can affect the battery system adversely.